Maximization of economic efficiency, the safe operation of facilities, minimization of negative environmental impact, and consistent control of product quality have all inspired an ongoing increase in the comprehensive deployment of increasingly sophisticated automated process control technology. Within the last 30 years, the technology has migrated from pneumatic control loop devices and electro-mechanical timer activated valve and motor switching to direct digital control by real-time computers. Initially, the methods deployed by computer controlled systems duplicated the traditional proportional (P), proportional-integral (PI), and proportional-integral-derivative (PID) controllers along with the use of valve and motor switching control enhanced by some straightforward boolean logic. Continuing exploitation of the computer environment further enhanced process control methodology to include adaptive controllers and systems with sophisticated capability for anticipating future manufacturing process states in order to define optimal control settings. An example of such an approach is described in "Integration of Model Development and Advanced Process Control", COPE-91, Oct., 1991, by Drs. MeCroskey and Wassick. This article is hereby incorporated by reference.
Process control methods, in general, seek to enable stable, efficient, predictable, and robust control of manufacturing systems in a dynamic context. This control characterization is generally considered to be more "optimal" in an economic sense than a manufacturing system that is unstable, inefficient, and "out of control". A reference to such a process control methodology indirectly utilizing one of the more sophisticated optimization methods is U.S. Pat. No. 4,723,214 to Frei which utilizes wind tunnel data to determine a technologically optimal relationship of the control surfaces and components in an aircraft using a Lagrange Optimization Program--the results of the optimizing study are input as a reference table in the process control machine. However, the patent to Frei does not describe functionality related to decision making using an objective function referencing changing monetary economic values related to components used in the system as part of the input data. The cost of operating the aircraft is assumed to be minimized if the aircraft is optimized without regard to fluctuations in the price of fuel or maintenance since the goal of optimization implicitly seems to relate to technical system stability, controllability, dynamic robustness, speed, and efficiency. Furthermore, the invention according to Frei does not periodically attempt to reconcile the set of inputs used to derive the appropriate flight control settings.
The focus of process control development has traditionally been directed to the technical dynamic and configurational needs of the machine being operated, the focus very naturally growing out of the migration of the methodology from its pneumatic control beginnings. Process control methods, however, have not traditionally attempted to incorporate real-time shifts in the monetary value of resources being used in conjunction with the system. The price/cost of oil, of jet fuel, of working capital, of electrical power, and of the items being used and manufactured by the system have been usually examined at times related to general business accountability by the personnel of the business operating the system. Some general adjustments to the rate of machine operation might be made at those times to reflect changing economic conditions as the business operation was evaluated as a whole. In terms of real-time execution, however, the constantly changing real-time economic conditions in the environment of the system being operated have not been extensively utilized as real-time system control input data even though they have always virtually impacted the efficient use of the machine in the more rigorous real-time sense. The effective cost of working capital actually does vary with each transaction performed within the world's monetary system, and the cost of electricity varies with the particular time of the day, week, or month, and also with each transaction performed within the global oil and gas industry. The cost of manpower can also shift as a function of the particular time of the day during which operation of the system is occurring since different hours of the day frequently carry different contractual compensation considerations.
The sophisticated growth of electronic communication today enables the values of a number of fluctuating economic variables to be monitored on an immediate and real-time basis, and modern computers can easily provide real-time interpretation of complex entities such as electric utility contracts. This enables real-time data from the economy as a whole to be acquired by the control computer system even as it also acquires real-time sensor data from the technical system. The use of the subsequently combined set of real-time economic and technical data in the operation of a system enables the implementation of economic operation to acquire an additional dimension of sophistication over the traditional method of focus on technical system data.
What is needed, therefore, for comprehensive economic optimization of a manufacturing system is an adaptive controller which can change the operation of the process to reflect both the real-time movement of prices (monetary values) in the market place for components used in the manufacture as well as the real-time technical status of the manufacturing system. The present invention implements a solution to this need.